Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/e4855b5da2f92857d97dc6193c5759fa.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563